For example, in the casting process, such as die casting, low pressure casting, and gravity casting, the forced cooling of a mold is conducted for the purpose of the stabilization of quality caused by the reductions in cycle time of the casting and the control of solidification of the molten metal injected into the mold cavity. Such forced cooling of a mold is generally conducted by pumping the cooling water, pressurized by a pressure pump, into the cooling passageway of the mold (e.g., Patent Document 1).
However, in the manner where the cooling water is pumped into the cooling passageway of the mold, a pressure loss occurs or a state of turbulence occurs when the cooling water flows through the piping system or the cooling passageway of the mold, which may cause the cooling water to be non-uniformly distributed to the whole flow passageway. Due to this, water deposit or cake is deposited at the locations where the cooling water is unlikely to flow, which may prevent the cooling water from being sufficiently supplied to the cooling passageway of the mold. Moreover, in the case where the mold is cracked due to thermal fatigue caused by long-term usage or the like, it is a concern that the cooling water may leak to the outside of the mold or into the cavity via the crack.
In order to avoid the aforementioned disadvantage, the means of forced cooling of the mold can be a suction pump connected to the outlet side of the cooling passageway of the mold whereby the cooling water is sucked by the suction force of the suction pump, so that the cooling water flows through the cooling passageway of the mold (e.g., Patent Documents 2 to 5).
[Patent Document 1] Japanese Patent Unexamined Publication No. 10-80758
[Patent Document 2] Japanese Patent Unexamined Publication No. 9-85420
[Patent Document 3] Japanese Patent Unexamined Publication No. 8-243713
[Patent Document 4] Japanese Patent Unexamined Publication No. 9-253825
[Patent Document 5] Japanese Patent Unexamined Publication No. 11-170024